Here's how it works: The National Weather Service describes the heat index using the time ... humidity is 65%, the heat index temperature is 121 degrees. That falls in the orange zone of the chart ...

The graph shows spikes and drops in temperature over the past 9,500 years, charting how much higher or lower each year’s temperatures are than the average temperature over the entire time period.

At the same time, the body ... subtract the wet-bulb temperature from the dry-bulb temperature to get the temperature difference. Finally, use the relative humidity chart (see below) to get ...